Abstraction functions, rep-invariants, and verification are the focus of Quiz 4. You should understand, evaluate, and modify the abstraction functions and rep-invariants for simple variations on the IntSet and Poly examples. You should also understand the verification of methods with respect to their specifications. If I give you a specification, and a Java implementation, you should be able to analyze (informally) whether the method is correct. In particular, I'd suggest studying the verification of the IntSet example, which we covered in detail in class.